[camarojoe]

As you probably already know, those caps fit a chevy rally wheel, both 14 and 15 inch diameters. I believe they came on police cars and service vehicles in place of the standard "derby" caps used on other passenger cars...not sure about the years used, but the chevy rally wheel was produced from 1967 until 1977, so they'll fit any of those wheels. For a long time I thought they were something the aftermarket came up with, and not an actual production piece, but i saw an NOS GM set a few years ago.